1. Field of the Invention
The present invention relates to an electromagnetic relay used in an industrial apparatus, an automobile, and the like.
2. Description of the Related Art
In general, an electromagnetic relay is constructed by a core, a bobbin into which the core is inserted, a winding wound on the bobbin, a yoke fixed to an end of the core, an armature coupled via a hinge spring to the yoke, and coupled to the other end of the core, a movable contact, a stationary contact, a base block for adhering the contacts thereto, and the like. An electromagnetic assembly including the core, the bobbin, the winding, the yoke, the armature, and the like is located at a predetermined position within the base block, and a contact spring assembly including the movable contact and the stationary contact is also located at a predetermined position within the base block (see: JP-A-60-249221). In this case, after these elements are assembled, a relationship therebetween is determined to thereby obtain a load of the armature, and thus establish a sufficient contact pressure between the movable contact and the stationary contact in an active mode.
Nevertheless, in practice the dimensions, strength, and the like of the elements of the relay fluctuate, and therefore, a contact gap between the movable contact and the stationary contact and an armature load characteristic also fluctuate in accordance with the electromagnetic relay. As a result, the contact gap and the armature characteristic are designed by taking into consideration the fluctuations of each of the elements.
Therefore, in the above-mentioned prior art, since an absorption force (coercive force) of an electromagnet must be designed to satisfy a maximum armature load characteristic, the size of the electromagnet, i.e., the size of the relay, is increased, and as a result, a power dissipation must be increased to cope with the increased size of the relay.